This project is based upon the utilization of a non-invasive canopy-spirometry-computer system for the prolonged measurement of spirometry and gas exchange in normal subjects and surgical patients. Computer processing of this data is performed on-line with eight computer-plotted graphs promptly available as a detailed summary of each study. The normal pattern of breathing of resting, supine adults is not well established, and the limited data available has involved the artifacts of using a tight-fitting mask or mouthpiece. Part of this proposal is to measure and analyze the breathing pattern of the series of adult men and women to establish normal values for tidal volume frequency, minute ventilation, inspiratory and expiratory time, mean inspiratory flow rate and mean expiratory dwell time. The simultaneous measurement of gas exchange with spirometry allows a unique opportunity to examine the correlation between ventilation and metabolism in normal subjects and in surgical conditions with varying levels of hypermetabolism. Preliminary studies have established the feasibility of this system for measuring the response to simulation using inspired CO2, or measured amounts of supine exercise. Such studies will contribute to our understanding of the control of ventilation in normal man, and guide the development of levels of stimulation which can be used safely in acute surgical patients. Our long-range goal is to develop knowledge of abnormal patterns of breathing which will allow early recognition of the loss of breathing reserve, provide a more sensitive means of following the results of therapy and perhaps to offer improved guidance for how soon patients should be weaned from mechanical ventilation, thus improving the safety and decreasing the extent of apprehension of such patients.